Barrier filter systems for aircraft engine inlets are typically positioned so that all intake air must flow through the filter prior to reaching the engine. In this way, the barrier filter can inhibit particles from reaching the engine and thereby prevent particle damage to the engine.
Some prior art inlet barrier filter systems for aircraft engines include a “bypass” door that can be opened in the event the barrier filter is clogged during flight. Such clogging may prevent sufficient air from reaching the engine. Thus, the bypass door may be opened during flight to greatly increase the airflow to the engine. While such bypass doors have generally been satisfactory, there are disadvantages.
Generally, bypass doors add to the cost and complexity of the filter system. Accordingly, a simple bypass door is needed.
One prior art design incorporated the bypass door into a filter panel. In other words, the filter panel was pivotable so that air could pass around the panel if the filter was clogged. However, in the prior art design, the filter panel pivoted upward about its rearward edge so that it opened toward the front of the aircraft. This design causes problems, for among other reasons, the opened filter panel acts as a “scoop”, drawing particles and debris, including ice, into the intake. These particles and debris can thereafter reach the engine and cause damage to the engine. Also, the design is complicated by the fact that the filter panel is not adjacent the outer contour of the aircraft. Rather, the panel is under a cowling. Accordingly, an improved filter panel system with a simple bypass that minimizes particles and debris is needed.